Skin fibroblasts from human controls or from patients with familial dysautonomia (FD) have been grown in tissue culture. Beta-Nerve growth factor (NGF) has been measured in extracts from both type of cells, using a radioimmunoassay and a bioassay. The FD cells have contents of NGF as measured by RIA comparable to the controls. However, the biological activity of the FD samples is about one-tenth that of the controls when expressed as biological units of activity per ng Beta-NGF as measured in the RIA. Stimulation of Beta-adrenergic receptors in both cell lines with 1-isoproterenol results in a 17-170 fold rise in intracellular cyclic AMP in 10 min. The NGF content of the control fibroblasts increased 50-300% after 3-4 hours of exposure to isoproterenol whereas there was no change in the NGF content of the FD cells at any time.